Fluid machinery in the related art includes a compressor, an expander and the like. The compressor is taken for example.
During motion, the positions of the center of mass of a rotating shaft and cylinder of a piston-type compressor in the related art are changed. A crankshaft is driven by a motor to output power, and the crankshaft drives a piston to make a reciprocating motion in the cylinder to compress gas or liquid to apply work, so as to achieve the aim of compressing gas or liquid.
A traditional piston-type compressor has several defects as follows. In the presence of a suction valve and an exhaust valve, the suction resistance and the exhaust resistance are increased, and the suction and exhaust noises are increased. A large lateral force is exerted on a cylinder of the compressor, and the lateral force applies an idle work, thereby reducing the efficiency of the compressor. A crankshaft drives a piston to make a reciprocating motion, and the eccentric mass is large, thereby causing large vibration of the compressor. The compressor drives one or more pistons to work via a crank-connecting rod mechanism, thereby being complex in structure. The lateral force exerted on the crankshaft and the piston is large, and the piston is easy to abrade, thereby reducing the sealing property of the piston. Moreover, the volume efficiency of the conventional compressor is low due to the reasons such as clearance volume and large leakage, and is difficult to increase.
In addition, the center of mass of an eccentric portion in a piston-type compressor makes a circular motion to generate a size-invariable and direction-variable centrifugal force, this centrifugal force increasing vibration of the compressor.